Impact tool



Aug. 10, 1943. F. P. FORSS 2,326,347

IMPACT TOOL /illl INVENTOR. F/r/f/of A Fo/Pss W A BY @wam A TTORNEY.

F. P. FORSS IMPACT TOOL Filed Oct. 9, 1941 4 Sheecs-Sheet 5 IN VEN TOR.

F/P/r/f/o/f ,0, ,rags-S ATTORNEY.

Aug l0, 1943. F. P. FoRss 2,325,347

IMPACT TOOL Filed oct. 9, 1941 4 sheets-sheet 4 l! 1 f5 7K ./4/

A TTORNEY.

Patented Aug. 10, 1943 nvrPAc'r 'rooL Frithioi P. Forss, Aurora, ill.,assignor to Indei pendent Pneumatic Tool Company, Chicago, Ill., acorporation of Delaware Application october 9, 1941, serial No. 414,228

ze claims. (c1. naz-4305) This invention relates to improvements inportable hand-held, self-contained motor driven impact tools forscrewing up and removing nuts andv bolts by power.

The principal object and purpose of my invention is to provide arelatively light, but powerful impact tool of an extremely strong andsturdy construction throughout, designed for setting and removing in aminimum of time relatively large nuts and bolts up to 11A" bolt size asvemployed in railroad shops, ship yards, constructors, automotive plantsand other heavy industries, the tool having suiiicient power for drivinglarger size nuts and bolts in some kinds of work where the torsionrequirements are not in the extreme.

A further object of the invention is to provide a tool in which the nutdriving and nut removing operations are of the impact type, asdistinguished from the ordinary power wrench, whereby no torque istransmitted to the operator in the work in a screwing up operation orloosening a tight or rusted nut in an unscrewing or removing operation.

A further object of the invention is to provide the impact members andthe anvil jaws of relatively heavy section and slidably mount the impactmembers in slots in the hammer element for rectilinear movement wherebythe impact members may be provided with relatively wide side surfacessubstantially co-extensive with the side surfaces of the slots and thejaws to respectively support the impact members in the slots and havedriving and impact engagement with the jaws throughout substantially thefull length thereof.

A further object of the invention is to provide momentum means actingindependently of the hammer element for automatically releasing theimpact members from the anvil jaws following each blow delivering impactthereon by positively moving the impact members out of the orbital pathof the jaws.

A further object of the invention is to provide said momentum means withrecesses to receive and position the impact members in the orbital pathof the jaws and cam means to move the impact members out of the path ofthe jaws in the rotation of the momentum means relatively to the hammer,

A further object of the invention is to provide coacting means betweenthe hammer and the momentum means to impart rotation to the latter andto control the movement thereof in positionving the recesses and the cammeans with respect to the impactmembers.

A further object of the invention is to utilize the co-acting elementson the hammer and the momentum means as a limiting stop to preventoverrunning of the hammer by the momentum means on the release of theimpact members and retain the recesses and the cam means in properpositions with respect to the impact members and the anvil jaws..

A further object of the invention is to provide means for setting saidco-acting elements for either direction of rotation.

And a further object of the invention is to provide a safety brake tostop the rotation of the motor when the throttle valve is closed andthereby give the operator complete control over the free spinning of aloose nut when removing the same to prevent the nut flying off the bolton being unscrewed therefrom.

The invention consists further in the features hereinafter described andclaimed.

In the accompanying drawings illustrating one embodiment of myinvention- Fig. l is a longitudinal sectional view with parts inelevation of my improved impact tool;

Figs. 2 and 2A are similar sectional views of the tool on a larger scalethan that employed in Fig. 1; Fig. 2 constituting a section of the lowerportion of the tool containing the impact clutch and Fig. 2A beingasection of theupper portion.

of the tool containing the driving motor and control valves therefor,one section being a continuation of another from the dividing line A-Abetween them, the casing for the reversing valve which would appear inthese views and 'also in Fig. 1 being omitted for clarity ofillustration;

Fig. 3 is a. transversey sectional view taken on line 3-3 of Fig. 1 withthe impact members in elevation and shown in driving and impact blowwith parts in elevation and showing the cam ring y lifted to raise thestop b ar above the shorter lugs on the cam ring;

Fig. 9 is a transverse sectional view taken through the motor section ofthe tool on line 9-9 of Fig. 1;

Fig. 10 is a perspective View of the hammer element;

Fig. 11 is a similar view of the anvil element;

Fig. 12 is a similar view of the cam ring;

Fig. 13 is a fragmentary longitudinal sectional view with parts inelevation of the reversing valve to be herein described;

Fig. 14 is a transverse sectional view taken on line III-I4 of Fig. 1 toshow the porting on the exhaust side of the tool;

Fig. 15 is a sectional view showing the portion 4 of the reversing valvein Fig. 14 turned to its reversing position;

Fig. 16 is a sectional view of the operating valve for the brake disc ona larger scale than employed in Figs. 1 and 2A; and

Fig. 17 is a diagrammatic view to be later referred to.

While the tool may be driven by any preferred form of motor, yet I haveshown the tool in the present disclosure equipped with a pneumaticallyoperated reversible motor of the rotary type having a revoluble rotor Iand a surrounding stationary cylinder bushing 2. These parts are housedwithin the cylinder case 3 of the outer casing of the tool as shown inFigs. 1 and 9. I'he cylinder bushing 2 is held against rotation in thetool case by being keyed throughout its length to the cylinder case 3and contains the rotor I in eccentric relation to the bushing 2 as shownin Figs, 9 and 14. It will be noted from these figures that the rotor Ihas peripheral contact with the inner cylindrical surface of thecylinder bushing 2 at one point in its circumference to divide thechamber formed by the cylinder bushing into high and low pressuresections, respectively, as in motor, devices of this character.'

Slidable blades 4, 4 are carried by the rotor I in radial slots 5, 5therein and these slots are supplied at their bottom portions with thecompressed air or other pressure fluid furnished to the tool to hold theouter edges of the blades at the proper points in contact with the innercylindrical surface of the cylinder bushing 2. The porting arrangementfor accomplishing this result is not shown, constituting no part of mypresent invention.

The trunnions or shaft extensions 6, 'I at the opposite ends of therotor I are journalled in the tool assembly and extend through the upperand the lower centerplates 8, 9 which close the opposite ends of thecylinder bushing 2 as shown in Fig. 1. The centerplates 8, 9 are mountedin the cylinder case 3 and are held against rotation by dowel pins orotherwise. The shaft sections B, I of the rotor are journalled inanti-friction bearings ID, II supported in the tool assembly at thecenterplates 8 and 9, respectively. 'Ihese bearings are of extremelyheavy size.xparticular1y the escasa? lower bearing II which receives themore severe service being next' adjacent to the impact clutch mechanismto be presently described'. The lower shaft 'I has direct connectionwith the hammering element of said clutch.

The upper shaft 6 of the rotor is equipped with a governor valve toautomatically control the amount of pressure fluid supplied to the motorin the operation of the tool in accordance with iis speed of rotation.'I'his feature forms no part of my present invention, but as shown inFig. 2A comprises generally an axially movable valve member I2 whichcontrols a port I3 in a. bushing I4 xed in the handle section I5 of thetool in crossing relation to its main presure fluid supply passage I6.The latter connects into the bushing I4 through a port I'I thereinbeyond the limit of outward movement of the valve member I2. This memberis moved inwardly by the live air pressure acting on its upper surfaceand is given outward movement to partially close the port I3 by pivotedweights I8, I8 carried by and rotating with the shaft section 6. Theseweights swing outwardly from the axis of the rotor in response tocentrifugal force as the motor speed accelerates and move the valvemember I2 to partially close the port I3 to reduce the amount of airpressure supplied to the motor when running at free speed. When underload, as when screwing up or unscrewing a nut or a bolt, the centrifugalforce decreases and the fluid pressure on the valve member I2 moves ittowards the shaft 6 to open the port I3 and supply a greater volume oflive air to the motor to increase its driving power.

The handle section I5, which may be of the grip type as shown, issecured to the upper end tion I5 between its main supply passage I6 andthe nipple 20. Said valve is movable to open position through a triggerelement 22 pivoted on the handle section I5 and engageable by theoperator from the outer side of the handle.

When the throttle valve 2| is unseated com- I pressed air is supplied tothe tool motor through the passage I6 and the other passages connectedtherewith in the handle and cylinder sections I5 and 3, respectively.One of these passages in the handle section is shown at 23 in Fig. 2A.This passage surrounds the bushing I4 and connects with the port I3therein. The passage 23 connects with a passage 24 'in the cylinder case3 at one side of the reversing valve bushing 25 as shown in Fig. 9. Whenthe reversing valve 26 in this bushing is turned to the full lineposition shown in Fig. 9, the ports 21, 2s in the bushing 25 connect thepassage 24 with a passage 29 in the cylinder case 3 and leading to oneor more ports 30 in the cylinder bushing 2. These ports 30 are spacedalong the length of the cylinder bushing 2 and supply live air to therotor I on the now high pressure side of the motor. The rotor I is nowrotated in a clock-wise direction as indicated by the arrow a in Fig.9-and the tool operates to screw up a bolt or nut as the case may be.

The exhaust from the motor at this time is from the low pressure side ofthe rotor through one or more ports 3| in the cylinder bushing 2 andconnected with a. space 32 between the cylinder bushing and the cylindercase 3 at the side of the ports 3|. The exhaust ports 3| are distributedalong the length of the Icylinder bushing 2 and the space 32 connectswith an exhaust passage 33 in the cylinder case 3 as shown in Fig. 14.At this location the reversing valve bushing 25 has ports 34, 35, theformer being connected with the passage 33 and the other being connectedwith the main exhaust outlet 36 of the tool in the cylinder case 3 asshown in Fig. 14. .At this port, the reversing valve 26 has a solid bodyportion 31 and a cut-away portion providing a recess 38 which when thevalve is in the position shown in-full lines in Figs. 9 and 14 connectsthe exhaust passage 33 with the main exhaust outlet 36. At this-time theinterior of the cylinder bushing 2 on the low pressure side of the rotoris also connected with the exhaust outlet 36 through ports 39 in thecylinder bushing 2 and a passage 40 in the cylinder case 3 as shown inFig. 9. The reversing valve bushing 25 has ports 4|, 42 which connectthe passage 40 with a passage 43 in the cylinder case 3 leading t'o themain exhaust outlet 36. The web portion 44 of the reversing valve 26 atthe ports 4|, 42 divides them from the ports 21, 23 which are nowsupplying pressure fluid to the high pressure side of the motor torotate it in a screwing up direction.

It will be noted that the ports 30 and 39 in the cylinder bushing 2 areon opposite sides of its line of contact with the rotor l. Hence, whenthe rotor l is being rotated to drive a bolt or nut, the ports 30 arethe inlet ports on the high pressure side of the motor, while the ports39 are on the exhaust side. The reverse relation exists when thereversing valvel26 is turned to reverse the direction of rotation of themotor as will be presently described. The ports 39 have the samearrangement and longitudinal spacing as the ports 30.

The cylinder bushing 2 has a second set of ports 45 Asimilar to theports 3|. 'Ihe ports .45 are on the side of the cylinder bushing 2 oppo'site to the ports 3| and connect with a space 32a opposite to the space32 and similar thereto. The space 32a is on the exhaust side of themotor when running in reverse and connects with an exhaust passage 46 inthe cylinder case 3 as shown in Fig. 14. When the rotor is running in ascrewing up direction the passage 46 is closed off from the exhaust 36by the solid body portion 31 of the reversing valve 26 closing a port 41in the valve bushing 25 and connected with the passage 46. The space 32ais separatedfrom the space 32 by rib formations on the outer side of thecylinder bushing 2 about the boundaries of the respective spaces. Theaxial ribs are marked b and c in Figs. 9 and 14.

When the reversing valve 26 is turned to the dotted line position d inFig. 9 the inlet passage 24 is connected with the passage 49 and theports 39 and pressure fluid is now supplied to the opposite side of therotor to rotate the rotor in reverse direction or in a direction tounscrew a nut or bolt. At this time the motor exhausts through ports 45,space 32a, passage 46, ports 41 and 35 and main outlet 36 as indicatedin Fig. 15. The interior of the cylinder 2 on the exhaust side of themotor also exhausts through ports 30, passage 29, ports Zilandv 42 andexhaust'v passage 43 as seen from Fig. 9. The space 32 and the passage33 which are now on the high pressure side of the motor are closed tothe exhaust ouuet as by the solid body portion 31 of the reversing valve26 closing the port 34 as shown in Fig. 15.

The reversing valve 26 is in the form of a turning plug as best shown inFig. 13. The web section 44 is between the solid body section 31 4 atthelower end of the plug and a circular top section 48. The sections 31and 48 rotatably mount the plug in the bushing 25 and the upper end ofthe plug is provided with a shaft-like extension 49 to receive amanually operable turning lever 50. The latter is clamped to the plugfor turning it from the outer side of the tool case. A spring presseddetent 5| carried by the handle section l5 and engageable with the shaftsection 49 holds the valve plug 26 in either of its `\operativepositions, that is, one for a clockwise rotation of the rotor and theother for a reverse rotation. For assembling and disassembling purposesthe valve plug 26 and its extension 69 are made separate being connectedby a tongue and slot arrangement as indicated in dotted lines in Fig.13.

The impact clutch mechanism is located within the lowerl portion 52 ofthe tool casing below the driving motor, the casing 52 being secured tothe lower end of they motor case 3 in any preferable manner as by bolts53. The impact clutch comprises axially alined hammer and anvil elements54, 55 as clearly shown in Figs. 2, 10 and 11.

The hammer element 54 is preferably a solid, one-piece drop forging ofmetal of the desired quality and is generally cylindrical in form asshown in Fig. 10. The upper cylindrical end portion 56 of the hammerelement fits about and is connected to the lower end portion of thelower shaft section 1 of the rotor to be driven therebyas shown in Fig.2. As indicated in Figs. 2 and 10, the hammer element 54 has a heavy,

splined connection with the shaft section 1 as at 51 to provide a directdrive connection between them.

The anvil element is also a one-piece drop forging of similar metal and,as shown in Fig. 11, comprises an upper or head portion 58 provided witha pair of upwardly extending jaws 59, 59 of relatively heavy section.These jaws are integral with the head section and are disposed indiametrically spaced relation as detailed in Fig. 11. The jaws 59 fitabout the lower cylindrical body portion 60 of the hammer element 54with sufficient clearance to permit free relative rotation of the hammerand anvil elements when disconnected by the impact members to bepresently described. The anvil element 55 has a lower shaft or spindleportion 6| also integral with the head section 58 and rotatably mounted'in a bearing bushing 62 fitted against rotation in the extreme lowerpart of the tool casing 52 as shown in Figs. 1 and 2.

The extreme lower end portion 63 of the anvil spindle 6| extends out ofthe tool case 52 when the parts are assembled and is preferably madenon-.circular in shape to receive and rotate a nut or bolt head engagingsocket member 64 as shown in Fig. 2. The connection between the lowerend of the spindle 6| and the socket 64 is releasableA comprising in theembodiment shown a cross-pin 65 fitting within line openings 66, 61 inthe respective parts and normally held in its connecting relation by asplit retainer ring 68 applied about the socket in the region of the pinas shown in Figs. 1 and 2. The connection referred to enables sockets ofdifferent nut or bolt sizes to be used with the tool. the socketengaging end 63 of the anvil spindle Bl is made to t all standard impacttype sockets up to 1" square drive size.

As shown in Fig. 2, thc hammer element 54 bears against the anvilelement 55 between its jaws 59. To provide a revoluble connection forthe parts the lower end face 69 of the hammer elementis made radiallyfiat and circular and fits a complementary face on the upper surface ofthe anvil element at the base of the jaws 59. Interposed between theparts at this point of contact is a centering pin 1I. is cylindrical andfits within alined axial bores 12, 13 in the hammer and the anvilelements 54, 55, respectively, as shown in Fig. 2. The member 1I has anenlarged portion 14 in the hammer bore 13 to seat the pin between thehammer and anvil elements and to project the upper smaller end of thepin into the path of the impact elements 15, 15 with which the hammer 54is provided. In this way the pin 1I provides a limiting stop for theimpact members 15, the latter having notches 1|a at their lower inneredges to receive the pin 1| to retain as much mass as possible for theimpact members for blow delivery purposes. The pin 1i also prevents theimpact members coming into contact when moved inward to their fullestextent and hence, no opportunity is afforded for the impact memberstobind or stick together.

This member In practice,

of rotationzs imparted to the anvil"`55 when the. impact ,members engagethe surfaces- 59h ofthe jaws.

The y"cam ring-heretofore referred to is shown at 19.` This'ring ismomentum operated and acts automatically in the operation of the tool toslide the impact members 15 backwardly into the slots 16 to release theimpact members from the anviljaws 59 immediately following each hannner,blow of the impact members on the jaws. This occurs when the freeturningv of the anvil by the rotating hammer is resisted by the nut orbolt in a screwing up or an unscrewing operation. The cam ring 19 has aoating or over-running mounting about the hammer 54 between the upperends of the jaws 59 and an outwardly projectingl annular flange 80 onthe hammer 54 above the slots 16. An. annular bearing member 52a in thehousing 52 gives the ring 19 this support and position (See Fig. 2).

The cam ring 19 is also a drop forging, in onepiece of metal andcomprises an annular body portion 8| having a circular opening 82 to fitabout the cylindric body section 6U of the hammer 54. The cam ring 19 isprovided on its inner side with a pair `of circumferentially extendingrecesses 83, 83 diametrically disposed and joined by arcuate sections84, 84 of the same diameter as the opening 82. The purpose of therecesses 93 is to allow the impact members 15 to move outf wardly intothe orbital path of the anvil jaws The impact members 15 are also dropforgings in the form of solid rectangular blocks of the desired heavysection and blow delivering metal. The impact members 15 are slidablymounted in slots 16, 16 in the hammer element 54, one for each impactmember. The slots are radially disposed in respect to the axis of thehammer and constrain the impact members to a linear sliding movement,outwardly in response to centrifugal force and inwardly by the action ofthe cam ring thereon as presently described. The slots 1B arediametrically disposed and open into the hammer 'bore 12 so that theimpact members 15 may be The slots 16 are disposed in the hammer 54 toextend above and below the upper end of the jaws 59 when the parts areassembled as shown in Fig. 2. With this arrangement, the lower bodyportions 11 of the impact members 15 are positioned to engage the jaws59 when the impact members project into the orbital path of the jaws,whereas the upper portions 18 of the irnpact members are above the upperends of the jaws for engagement by the cam ring heretofore referred to.The arrangement described is shown in Fig. 2. The lower body portions 11of the impact members 15 have substantially flat striking surfaces 15a,15b on their opposite sides to engage the substantially dat impactreceiving surfaces 59a., 59o on the opposite sides of the jaws 59. Withthe striking and impact receiving surfaces so disposed, it will be seenthat the impact members 15 may drive the anvil 55 in oppositedirections. The anvil 55 is rotated clock-wise in a screwing `upoperation when the impact members 15r engage the jaws at their impactre- `eiving surfaces 59a, whereas a reverse direction sired relationshipbetween the recesses 83 and the impact members 15 and also impartsrotation to the cam ring. As long as the nut or bolt being driven isfree to turn, the impact members 15 retain driving engagement with theanvil jaws, being held in that relation by the centrifugal forcegenerated by the rapidly rotating hammer.

When the rotation of the anvil element 55 is arrested as heretoforementioned, the camiing 19 continues to rotate by its momentum and forcesthe impact members 15 back into the slots 16 to release the drive of thehammer on the anvil element. This occurs because the cam surfaces 81 ofthe ring at the ends of the recesses 83 move the impact members 15 outof the rccesses. As the arcuate surfaces 84 of the cam ring pass overthe outer ends of the impact members 15 the latter are retained withinthe outerv circumference of thehammer 54 and the latter is free to bedriven by the motor relatively to the anvil 55. This carries the impactmembers 'l5 past the anvil jaws 59 as will be seen from Fig. 5 and thestopbar 85 picks up the `cam ring 19 to iposition the recesses 83beyondthe jaws to again receive the impact members on freeing the jaws.The impact members 15 are now moved outwardly by centrifugal force intothe spaces between the anvil jaws and the motor now operating at fullspeed carries the impact members with a striking blow against the sidesurfaces of the jaws towards which the movement is directed.

The anvil 55 being still held against'rotation by the tightened orpreviously tightened nut or bolt is partially turned by this blow andthe nut or bolt is further tightened or loosened as the case Y may be.At the time of striking or impact, theV members 15 and the hammer 54come to an abrupt stop. In fact, the impact members 15 heavy rotationalhammer blows are struck in rapid succession against the anvil jawsV 59to eiectively tighten or loosen the nut or bolt depending on thedirection of rotation of the tool motor.

The recesses 83 open downwardly through the lower side of the cam ring19 to t over the upper end portion 18 of the impact members 15. This isshown in Fig. 2. The outer end portions of the impact members at the camring are rounded or curved as indicated at e, e in Figs. 3 and 5 forease in passing over the cam surfaces of the cam ring and the anvil jaws59. The recesses 83 in the cam ring 19 have the same circumferentialextent for systemetrical action on opposite sides of the ring. Y

The anvil jaws 59 are so proportioned and arranged that the hammer 54may rotate through a full half revolution in moving an impact mem# berfrom one jaw to the next in striking a blow. This is due to the factthat the circumferential distance from the impact receiving surface ofone jaw 59 in the direction of rotation is approximately 180 to 4theimpact receiving surface of the next jaw. This is indicated in thediagram in Fig. 17. Hence, when an impact member 15 is movedby the camring to release an anvil jaw as shown in Fig. 5, the hammer 54 incarrying said impact member to the next jaw travels a full halfrevolution. With this arrangement relatively heavy and solid blows maybe delivered to the anvil because of the fact that the hammer mayaccelerate and come to full speed before delivering its blow. Thisaccleration of the hammer also has the advantage of enabling the hammerto overtake the cam ring to insure having the recesses 83 in the camring properly located to receive the impact members as soon as theyV arecanied free of the jaws.

The stop bar 86 is carried by the hammer 54 in a cross-slot 88 thereinabove the slots 16 as best shown in Figs. 2 and 10. The slot 88 extendscompletely through the hammer body in the same position as the slots 16and is directly above the same. The slot 88 while it extends above andbelow the flange 88 terminates at its bottom slightly above the uppersurface of the cam ring 19. This positions the bar 86 just above theupper surface of the cam ring and locates its end portions 86a, 86h inthe path of a series of upright lugs 89, 98 on the cam ring andprojecting above the same. The lugs 89, 98 are diametrically and.alternately arranged with a 45 degree spacing between them as shown inFig. 4. The lugs 89 are slightly longer than the lugs 98. Thisterminates the upper ends of the lugs 98 just below the flange 88 on thehammer. The lugs 89 extend to about the upper surface of this ange, theinner upper edges of said lugs being recessed as at 98a to accommodatethe flange 88 as shown in Fig. 12. l

The bar 86 drives the cam ring 19 through the longer lugs 89. theshorter lugs 98 serving as stops to prevent overrunning of the cam ringwhen acting under momentum. When the tool is rotated forwardly, the baracts on one side of the lugs 89 as shown in Fig. 4. When rotating thetool in reverse the bar drives through the opposite sides of the lugs89. To adjust the bar 86 to operate on either side of the lugs 89, it isnecessary to shift the bar with respect to the lugs. The shiftingmechanism is automatic in action and is constructed as follows:

Surrounding the hammer 54 in the region of the bar 86 is a shifter ring9|. This ring :lits over the opposite ends of the bar 86 and has aninwardly directed annular flange 92. The latter, as shown in Fig. 8,extends under the outer end portions of the bar 86 and lifts the barwhen the ring 9| is raised axially upward as illustrated in Fig. 8. Thismovement carries the bar 86 above the upper ends of the shorter lugs 98and permits the bar to be rotated with the hammer over the shorter lugsto operate on the desired operative sides of the longerlugs 89. Hence,for a forward or screwing up rotation the bar 86 engages the sidesurfaces 89a of the lugs 89 as shown in Fig. 4, while for a reverserotationthe bar 86 engages the opposite surfaces 89h of the lugs 89. Ina reverse rotation of the tool the impact members 15 drive against theimpact receiving surfaces 59h and the clutch releases through thereverse action of the cam ring 19. i

The shifter ring 9| holds the bar 89 against endwise displacement, theouter annular wall 93 of said ring being over the outer ends of the baras shown in Figs. 1, 2, 4, 5 and 8. To assemble the parts, the shifterring 9| has a slot 94 in its annular wall 93 to pass the bar 89 when theslot and the bar are brought to register. Thisslot is shown in Figs. 4and 6. A split spring band 95 is located within the shifter ring 9| topartially close the slot 94 to retain the bar 89 within the ring. Atleast one end of the band 95 is bent at right angles to stop the ends ofthe band at the slot 95 and to also permit the band being pulled out orthreaded into the slot when applying or removing the band.

The lifting mechanism for the shifter ring 9| comprises a plurality ofcircumferentially spaced piston element 96, 96 as shown in Figs. 1, 2, 7and 8. The pistons 96 are mounted in downwardly directed cylinders 91provided on the lower centerplate 9 of the motor assembly. The ring 9|is secured to the piston elements 96 by screws 98, the latter extendingthrough holes 99, 99 in the top wall |88 of the shifter ring. The headsof the screws 98 engage against the under side of the wall |88 and raisethe shifter ring 9| when the pistons 96 are moved upwardly. When theshifter ring is lowered as shown in Fig. 2, it may rest on a flange 52hprovided in the casing section 52.

Each cylinder 91 is provided with a pair of ports |8|, |82. These portsare axially spaced, the port |8| being adjacent to the upper end of thecylinder and the port |82 being adjacent to the lower end of thecylinder. The lower port |82 connects with a live air channel |83 formedin the cylinder case 3 on the outer side of the centerplate 9 as shownin Figs. 1 and 2. A passage |84 in the cylinder case 3 connects thechannel |83 with a space |85 between the cylinder bushing 2 and thecylinder case 3 as shown in Figs. l and 9.v This space extends toadjacent the upper end of the cylinder bushing 2 and is connected by apassage in the case 3 with a passage |01 inthe handle vsection I5. sage|01 has direct connection with the live air supply passage l0 in thehandle as shown in Figs. 1 and 2A. With this arrangement when thethrottle valve 2l is unseated, live air is supplied to the cylinders 91through the lower ports |02 and the pistons 99 are moved upwardly tolift the bar v09. The pistons 99 have lower `pressure areas |00 for thisaction as shown in Figs. 1, 2 and 8. The pistons 9 5 may be movedupwardly because the upper ends of the cylinders 91 are normally open tothe exhaust on the low pressure side of the motor through the upperports |0| and the connected arcuate slot |09 in the upper surface of thecenterplate 9 within the diameter of the cylinder bushing 2 as shown inFig. 9. This slot extends on opposite sides of the center line of therotor I, and" hence has portions on the low and the high pressure sidesof the motor in either direction of rotation. With this arrangement,while the cylinders 91 may exhaust in the upward movement of the pistons96, live air may also enter into the upper ends of the cylinders fromthe high pressure side of the motor and act on the larger upper pressureareas of the pistons 96 to immediately move the pistons 96 downwardly tolower the ring 9| to its normal position. This action occurs rapidly oneach unseating of the throttle valve 2| and the position of the bar 05is not changed as to the lugs on the cam ring unless the motor is setfor a reverse rotation. 'I'he upper ports IOI are connected with theslot |09 by a channel ||0 about the outer edge of the centerplate 9 asshown in Fig. 2. This channel like the channel |03, extends to all ofthe cylinders 91 with which the device'is provided. They are three innumber in the embodiment disclosed as will be seen from Fig. 7.

The brake device to prevent over-running or spinning of the rotor I whenthe power is cut off, comprises a brake disc III overlying the upperwall |00 of the shifter ring 9| and seated on a shoulder ||2 on thehammer 54 at the base of its upper cylindrical portion 56 as clearlyshown in Fig. 2. This disc III is held from rotation with the hammer 54by the pistons 96 and a plunger ||3. The pistons 90 extend throughopenings in the disc as shown. The plunger |I3 is slidably mounted abovethe disc III in a cylinder I.|4 in the centerplate 9 as shown in Figs.1,12y and 8. The plunger I|3 has a reduced lower end portion ||5` toextend downwardly through an opening I I6 in the disc |II to hold thedisc against rotation and to provide a shoulder to press the discagainst its seat II2 on the hammer 54. The shift ring 9| has a hole I|1to receive the lower end of the plunger II 3 when the ring is lifted.This allows for close spacing of the parts for compactness inconstruction.

The action of the plunger I |3 is controlled automaticallyvby a valveIIB shown in-Figs. 1, 2A

and 8, but detailed in Fig. 16. This valve is in the portion of thecylinder bushing 2 at one of the rib sections b. The lower end of thepassage |23 is connected with the cylinder ||4 by a port |24 in thelower centerplate Sas shown in Figs. l and 8. The valve member ||8 isprovided on its outer side with upper and lower annular channels |25,|28, respectively. The bushing ||9 is provided with an upper port |21which connects with the upper channel |25 when the valve member II8 isin its uppermost position as shown in Figs. 2A and 16. Port |21 connectswith a live air supply passage |28 through a port |29 both in the handlesection I5 as shown. It will be noted that the passage |28 is connectedinto the air supply for the tool on the advance side of the throttlevalve 2|. Hence, as soon as the tool is connected to the air supply liveair is immediately conveyed'to the valve member I|8 through the passageI 28 and ports |29 and 21. This subjects the pressure areas |30, I3| onthe valve to live air pressure and the valve member II8 is movedupwardly to register its port |32 with the channel |25. Port |32connects with the bore |20 in the valve member and pressure fluid is nowsupplied to the cylinder |I4 through the passage |23. The plunger 3 isnow forced downwardly by live air pressure and passes the disc I Iagainst the seat |I2 on the hammer 54 to stop its rotation. s

The upward movement of the valve member I8 is stopped by contact of theupper end of said valve member II8 with a shoulder |33 about a port |34in the handle section I 5 above the valve bushing ||9. The port |34connects with the supply passage I6 in the handle I5 and subjects theupper closed end ofthe valve member ||8 to live air pressure on openingthe throttle valve 2 I. As the upper end of the valve has a greaterpressure area than the shoulders |30, I3I, the valve member I|8 is moveddownwardly as soon as the throttle valve is unseated. This moves theport |32 out of register with the channel |25 and carries said port intoregister with the channel |26. The bore |20 of the valve member ||8 isnow open to the exhaust ports which are provided for the valve and thepressure of the plunger ||3 on the disc |||y is released freeing the`motor of the brake.

The exhaust ports referred to comprise ports |35, |36 in valve bushing 9and a registering port |31 in the handle section I5 as shown in Fig. 16.

'Ihe statements of operation employed throughout the foregoingdescription of the structure of the tool and its parts are believed topresent a full description of the operation and use of the tool.summarized briefly, however, the operation of the tool is as follows:

To screw up a nut or a bolt to a tight seat, f

the tool is held in the hands of the operator by the handle-section |5and a dead handle, if one is provided at the side of the tool, and itssocket E4 is applied over the nut or bolt to be driven indicated at I 38in Fig. 1. The motor is then set in operation by opening the throttlevalve 2| to supply compressed air to the motor. The reversing valve26.at this time is set towards the right to rotate the motor in aforward or screwing up direction. On opening the throttle valve 2|, thelive air acts on the brake controlling valve ||8 to automaticallyrelieve the motor of the holding effect of the brake disc ||I and thetool motor rotates to speed. The hammer 54 being directly connected withrotor lI rotates at the same speed as the rotor and the impact members Iare moved by centrifugal force into the orbital path of the anvil jaws59. As soon as the impact members engage the jaws 59 the anvil element55 is connected to the hammer and the two rotate in unison to screw upthe nut or bolt to its seat. The cam ring 'I9 is picked up by therotatingr hammer 54 through the ystop bar 8'6 and the lugs 89 androtation is imparted to the cam ring with the outer ends of the impactmembers 'I5 within the recesses 83 of the ring. 'I'his connection isretained until the nut or bolt seats against the Work, whereupon'further rotation of the anvil element 551s arrested and the cam ring 'I9continues to rotate by its momentum to withdraw the impact members 'I5from the anvil jaws 59. This releases the connection between the hammerand the anvil elements I and the hammer is free to be rotated by thetool motor. Inthis relative rotation the motor speeds up, catching upwith the cam ring and setting the recesses 83 to vagain receive theimpact members as soon as they are carried past the anvil jaws.Centrifugal force again operates to slide the impact members I5 into thespaces between the anvil jaws and a positive, direct heavy rotationalhammer blow is struck by the impact members against the anvil jaws nextto be engaged. This turns the anvil element with suicient torque tofurther tighten up the engaged nut or bolt. The operation repeats aslong as the tool remains engaged with the nut or bolt and a series ofdirect, positive heavy rotational hammer blows are imparted in rapidsuccession against the anvil jaws to adequately tighten the nut or boltin the continued rotation of the tool motor. When the nut or bolt hasbeen tightened to the extent desired, the tool is removed from the workand engaged with the next bolt or nut to be driven.

For a reverse rotation, as when unscrewing a tight or rusted bolt ornut, the reversing valve 26 is set towards the left before applying thesocket 54 of the tool to the selected -nut or bolt. 'I'he throttle valve2| is then unseated as before and the impact members 'I5 connect theanvil 55 with the rotating hammer 54. If the nut or bolt is so tightthat it does not respond immediately to the torque of the tool motor,the impact members are withdrawn from the anvil jaws by the action ofthe cam ring 19, now operating in reverse, and a series of positive,direct, rapid rotational hammerheavy blows are imparted to the anviljaws as the impact members move into and out of the spaces between thejaws. These blows soon break the nut or bolt loose and the motor is thenfree to rapidly unscrew the nut by reason of the clutched engagementbetween the hammer and the anvil.

As soon as the nut is free, the operator may control the spinning of themotor by opening and closing the throttle valve ZI. On closing the valve2|, the live air pressure supplied to the tool at thesupply-hose pressesthe brake plunger H3 against the brake disc II I and stops the rotationof the hammer and the connected anvil. In this way the tool is underfull and complete control and the operator can prevent a nut from flyingolf a bolt when unscrewed. This feature is of particular value whenremoving large nuts overhead.

As heretofore stated the tool is relatively light in weight, for ease inhandling and manipulation, yet suiliciently strong, rugged and powerfulfor heavy duty operations. The impact members 15 and the anvil jaws 59are of relatively heavy solid section to electively drive the anvilelement by the hammer element when the two are in clutch and towithstand the direct, positive heavy rotational hammer blows which theim' pact members impart to the anvil jaws when the anvil element is heldagainst free rotation. With the impact members 15 in rectangular solidblock form and slidablymounted for rectilinear movement in slots in thehammer element, relatively wide surfaces are provided on the oppositesides of the impact members to adequately'support them within the slotsagainst the blow delivering impacts and to positively and directlyengage the impact receiving surfaces of the jaws throughout the fullextent thereof both axially and radially. 'I'his makes for positive andeertaln action at all times and the power factor of the tool is enhancedin tightening up nuts and bolts and in removing tight or rusted ones. Itwill be noted fiom Fig. 17 that the co-acting surfaces of the impactmembers and the anvil jaws are in parallelism when the parts areengaged.

The momentum acting cam ring 1S is important in that the releasing ofthe impact members I5 from the anvil jaws 59 is handled independently ofthe hammer and anvil elements. With this arrangement, a more direct andsolid -blow can be struck by the impact members due to the fact that thereleasing is handled by the floating or over-running cam independentlyof springs which would break or a slipping action which loseseiectiveness by wear as in tools as heretofore designed and constructed.Moreover, with an over-running cam ring the releasing action is positiveand sure and the impact members are moved completely back in their slotsto free the anvil jaws immediately following a blow delivering impactthereon.

The shifting means being responsive to the pressure iiuid supplied tothe tool automatically sets the'stop bar 86 or equivalent means carriedby the hammer by merely turning the reversing valve 26 for the selecteddirection of rotation for the hammer.

The brake feature is also important as above indicated and there isconsiderable advantage in having the impact members 'I5 held fromrotation with the hammer by the side walls of the slots in which theimpe-ct members are reciprocably mounted. It is to be understood thatthe brake device operates in either direction of rotation of the motor.The key between the cylinder bushing 2 and the cylinder case 3 will beYseen at |39 in Figs. 9, 13 and 14. Other and furtherv advantages of myimproved construction will be apparent to those skilled in the art towhich the' invention appertains. in the manner required for effectiveoperation and the cylinder bushing and rotor blades will be lubricatedautomatically from an oil reservoir contained within the handle sectionI5.

The details of construction and arrangement of parts shown and describedmay be variously changed and modified Without departing from the spiritand scope of my invention, except as pointed out in the annexed claims.

I claim as my invention: l. An impact clutch comprising a rotatablehammer, a rotatable anvil having spaced jaws,"

The tool Will be lubricated tracting means receiving rotation from thehammer and movable by momentum relatively thereto in its direction ofrotation upon the termina.- tion of an impact to automatically move theimpact members out of the orbital path of the jaws, and means fordriving the hammer.

2. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws, reciprocable impact members slidably carried by thehammer in slots therein and movable by centrifugal force into theorbital path of the jaws to deliver a succession of impacts to said jawsin the rotation of the hammer relatively to the anvil, revolvableretracting means rotatable independently of the hammer in its directionof rotati'on upon the termination of an impact to automatically slidethe impact members back into the slots and out of the orbital path ofthe jaws, and means for driving the hammer.

3. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws, reciprocable impact members slidably carried by thehammer in slots therein and movable by centrifugal force into theorbital path of the jaws to deliver a succession 'of impacts to saidlaws in the rotation of the hammer relatively to the anvil, revolvableretracting means rotatable independently of the hammer in its directionof rotation upon the termination of an impact to automatically slide theimpact members back into the slots and out of the orbital path of thejaws, said slots holding the impact members against rotation withrespect to the hammer, and means for driving the hammer.

4. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws, reciprocable impact members slidably carried by thehammer in slots therein and movable by centrifugal force into theorbital path o1' the jaws to deliver a. succession of impacts to saidjaws in the rotation of the hammer relatively to the anvil, revolvableretracting means receiving rotation from the hammer and rotatable bymomentum with respect thereto upon the termination of an impact toautomatically slide the impact members back into the slots and out ofthe orbital path of the jaws, and means for driving the hammer.

5. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws. reciprocable impact members slidably carried by thehammer in slots therein and movable by centrifugal force into theorbital path of the jaws to deliver a succession of impacts to said jawsin the rotation of the hammer relatively to the anvil, revolvableretracting means receiving rotation from the hammer and rotatable bymomentum relatively to the hammer upon the termination of an impact toautomatically slide the impact members back into the slots and out ofthe orbital path of the jaws, said impact members having relatively wideside surfaces substantially co-extensive with the side surfaces of theslots and the jaws,'respectively, to engage the impact members with theslots and jaws throughout approximately the full height thereof, andmeans for driving the hammer.

6. An impact clutch comprising a rotatable r hammer, a rotatable anvilhaving spaced jaws,

reciprocable impact members slidably carried by the hammer in slotstherein and movable by centrifugal force into the orbital path of thejaws to deliver a succession of impacts to said jaws in the rotation ofthe hammer relatively to the anvil, a momentum acting ring element aboutto deliver a succession ofimpacts to said jawsY in the rotation of thehammer relatively to the anvil, a momentum acting ring element about thehammer and receiving rotation therefrom, said ring having recesses andcam surfaces therebetween for cooperation with said impact members, saidrecesses serving to receive and position the impactmembers in theorbitalpath of the jaws and said cam surfaces serving in the rotation ofth ring by momentum relatively to the hammer upon the termination of animpact to slide the impact members back into the slots and out of thepath of the jaws, and means for driving the hammer. v

8. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws, reciprocable impact members slidably carried by thehammer in slots therein and movable by centrifugal force into theorbital path of the jaws to deliver a succession of impacts to said jawsin the rotation of the hammer relatively to the anvil, a momentum actingring element about the hammer and receiving rotation therefrom, .said

ring having recesses and cam surfaces thereber atively to the hammerwhen retracting the impact members and to position the recesses oppositethe impact members when free of the jaws.

9. An impact clutch comprising a, rotatable hammer, a rotatable anvilhaving spaced jaws, reciprocable impact members slidably carried by thehammer in slots therein and movable by cend trifugal force into theorbital path of the jaws to deliver a series of impacts on said jaws inthe rotation of the hammer relatively to the anvil, a momentum actingring element about the hammer at Said impact members, said ring havingrecesses and cam surfaces therebetween for cooperation with the impactmembers, said recesses serving to receive and position the impact members in the orbital path of the jaws and said cam surfaces serving inthe rotation of the ring by momentum relatively to the hammer to slidethe impact members into the slots and out of the path of the jaws uponthe termination of an impact thereon, means for driving the hammer,spaced lugs on the ring, and a cross-bar carried by the hammer andengageable with said lugs for controlling the rotation of the ring inpositioning the recesses and the cam surfaces with respect to the impactmembers.

10. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws,

said hammer having a pair of upper and lower slots, reciprocable impactmembers slidably mounted in one of the slots and movable by centrifugalforce into the orbital path of the jaws to deliver a series of impactson said jaws in the rotation of the hammer relatively to theanvil, amomentum acting ring element about the hammer at the impact members,said ring having cam means to positively slide the impact members backinto the slots and out of the orbital path of the jaws in the rotationof the ring by momentum relatively to the hammer upon the termination ofan impact on the jaws, means for driving the hammer, spaced lugs on thering, and a bar carried by the hammer in the other of the slots' andengageable with the lugs to control the rotation of the ring inpositioning the recesses and the cam surfaces with respect to the impactmembers and the jaws.

11. An impact clutch comprising a rotatable hammer, a rotatable anvilhaving spaced jaws having impact receiving surfaces on the oppositesides thereof, impact members movably carried by the hammer and movableby centrifugal force into the orbital path of the jaws to deliver aseries of impacts on said jaws in the rotation of the hammer relativelyto the anvil, said impact members having striking surfaces on theiropposite sides to strike the impact receiving surfaces of .the jaws ineither direction of rotation of the hammer, a momentum acting ringelement about the hammer and receiving rotation therefrom, said ringhaving cam elements acting on the impact members in the rotation of thering by momentum relatively to the hammer to move the impact members outof the orbital path of the jaws upon the termination of an impactthereon,`

means for driving the hammer in either direction, and shiftable meansfor setting the ring for action onthe impact members in either directionof rotation of the hammer.

12. A portable power driven impact tool of the character describedcomprising in combination, a reversible pneumatic motor, a rotatablehammer driven by said motor, an anvil rotatably mounted with respect tothe hammer and having spaced jaws having impact receiving surfaces ontheir opposite sides, impact members movably carried by the hammer andhaving striking surfaces on the opposite sides thereof, said impactmembers being movable by centrifugal force into the orbital path of thejaws to deliver a series of impacts on the jaws in either direction ofrotation of the hammer relatively to the anvil, automatic retractingmeans acting independently of the hammer upon termination of an impactto move the impact members out of the orbital path of'the jaws, andmeans operable by the iluid pressure supplied to the motor for settingthe retracting means for action on the impact members in eitherdirection of rotation of the hammer.

13. In a portable power operated impact tool comprising in combination,a reversible pneumatic motor, a rotatable hammer driven by said motor,an anvil rotatablymounted in respect to the hammer and having spacedjaws having impact receiving surfaces on their opposite sides, impactmembers movably carried by the hammer and having striking surfaces onthe opposite sides thereof, said impact members being movable bycentrifugal force into .the orbital path of the jaws to deliver a seriesof impacts on said jaws in either direction of rotation of the hammerrelatively to the anvil, revoluble retracting means receiving rotationfrom the hammer and rotatable by momentum relatively thereto upontermination of lan impact to automatically move the impact members outof the orbital path of the Jaws, and a shifter mechanism operable by thepressure fluid supplied to the motor for setting .the retracting meansfor action on the impact members in either direction of rotation ofthehammer.

14. In a portable power operated impact tool of the character describedcomprising in combination, a reversible pneumatic motor, a rotatablehammer driven by said motor, an anvil rotatably mounted in respect tothe hammer and having spaced jaws having impact receiving surfaces ontheir opposite sides, impact members movably carried by the hammer andhaving striking surfaces on the opposite sid'es thereof, said impactmembers being movable by centrifugal force into the orbital path of thejaws to deliver a series of impacts on said jaws in either direction ofrotationof the hammer relatively to the anvil, a momentum acting ringelement about the hammer and receiving rotation therefrom, said ringhaving means operable in the rotation of the ring by momentum in eitherdirection relatively to the hammer to move the impact members out of thepath of the jaws upon termination of an impact thereon, and a shiftermechanism operable by the pressure uid supplied to the motor for settingthe ring for action on the impact members in either direction ofrotation of the hammer.

15. In a portable power driven impact tool of the character describedcomprising in combination, a pneumatically operated motor, a hammerdriven thereby, an anvil rotatably mounted with respect to the hammerand having spaced jaws, impact members movably carried by the hammer andmovable by centrifugal force into the orbital path of the jaws todeliver a series of impacts on said jaws in the rotation of the hammerrelative tothe anvil, means acting in response to the rotation of thehammer to move the impact members out of the orbital path ofthe jawsupon the termination of an impact thereon, a brake element engageablewith the hammer, and piston means operable by the pressure fluidsupplied to the motor for pressing the brake element against the hammerfor stopping the rotation of the motor on turning oi the supply ofpressure fluid thereto.

16. In a portable power driven impact tool of the character describedcomprising in combination, a pneumatically operated motor, a hammerdriven thereby, an anvil rotatably mounted with respect to the hammer,an impact clutch for imparting a series of rotational hammer blows tothe anvil in the rotation of the hammer relatively to the anvil, abraking element engageable with the hammer, piston means, a main passagefor supplying pressure ud to the motor for rotating the same, a throttlevalve in said passage, and supplemental supply passages connecting thepiston means with the main supply passage on opposite sides of thethrottle valve to operate the piston means in one direction to press thebraking element against the hammer for holding the motor from rotationon closing the throttle valve and releasing the braking action on thehammer on opening the throttle valve.

17. An impact clutch comprising a reversible rotatable hammer, arotatable anvil having spaced jaws having impact receiving surfaces ontheir opposite sides, impact members movably carried by the hammer andmovable by centrifugal force into the orbital path of the jaws todeliver a series of rotational impacts on said jaws in the rotation ofthe hammer relative to the anvil, said impact members having strikingsurfaces on the opposite sides thereof to strike the impact receivingsurfaces of the jaws in either direction of rotation of the hammer, aring element about the hammer at said impact members, said ring elementhaving means acting in the rotation of the ring element by momentumrelative to the hammer upon the termination of an impact toautomatically move the impact members out of the orbital path of thejaws to release the hammer from the anvil, spaced driving and stop lugson the ring element, a drive bar carried by the hammer and engageablewith the drive lugs to impart rotation to the ring element and with thestop lugs to limit the extent of rotation of the ring element followingthe withdrawal of the impact members from the anvil jaws, a shift ringfor lifting the drive bar out of the path of the stop lugs to set thebar for driving against either side of the drive lugs, means for drivingthe hammer, and means for raising and lowering the drive bar.

18. In an impact tool of the character dev.scribed comprising incombination, a reversiblepneumatic motor, a hammer driven by said motor,a rotatable anvil having spaced jaws having impact receiving surfaces ontheir opposite sides, impact members movably carried by the hammer andmovable by centrifugal force into the orbital path of the jaws todeliver a series of impacts on said jaws in the rotation of the hammerrelative to the anvil, said impact members having striking surfaces onthe opposite sides thereof to strike the impact receiving surfaces ofthe jaws in either direction of rotation of the hammer, a ring elementabout the hammer at said impact members, said ring element having meansacting in the rotation of the ring element by momentum relative to thehammer upon the termination of an impact to automatically move theimpact members out of the orbital path of the jaws to release the hammerfrom the anvil, spaced driving and stop lugs on the ring element1 adrive bar carried by the hammer and engageable with the drive lugs toimpart rotation to the ring element and with the stop lugs to limit theextent of rotation of the ring element following the withdrawalof theimpact members from the anvil jaws, a shift ring for lifting the drivebar out of the path of the stop lugs to set the bar for engaging eitherside of the drive lugs,and means responsive to the pressure uid suppliedto the motor for raising and lowering the drive bar.

19. 'I'he combination as defined in claim 18 characterized by the factthat piston means operable by the pressure fluid supplied to the motorserve to raise and lower the drive bar.

20. The combination as defined in the claim 18 characterized by the factthat piston elements are in cylinders carried by the lower centerplatefor the motor and operable by the pressure fluid supplied to the motorserve to raise the orbital path of the jaws to deliver a series ofrotational blow impacts to said jaws in the rotation of the hammerrelatively to the anvil, automatic retracting means acting in responseto the rotationof the hammer for sliding the impact members back intothe slots and out of the orbital path of the laws upon the terminationof an impact, a centering element between the hammer and anvil andproviding a limiting stop for the impact members, and means for drivingthe hammer.

22. An impact clutch comprising axially alined rotatable hammer andanvil elements, the latter having spaced jaws, reciprocable impactmembers slidably carried by the hammer in slots therein and movable bycentrifugal force into the orbital path of the jaws to deliver a seriesof rotational blow impacts to said jaws in the rotation of the hammerrelatively to the anvil, automatic retracting means acting in responseto the rotation of the hammer for sliding the impact members back intothe slots and out of the orbital path of the jaws upon the terminationof an impact, a centering element between the hammer and anvil andproviding a limiting stop for the impact members, said impact membershaving recesses at their inner ends to reing the hammer.

23. In a portable power driven impact tool of the character describedcomprising in combination, a pneumatically operated rotary motor,rotatably mounted hammer and anvil elements, the hammer element beingconnected to the motor for rotation thereby, centrifugally operableclutch means interposed between said elements for releasably connectingthe same and for imparting a series of rotational hammer blows to theanvil in the rotation of the hammer by the motor relatively to theanvil, a brake disc about the hammer and engageable with a seat thereon,piston means for pressing the disc against said seat, means forsupplying a motive fluid under pressure to the motor and to the pistonmeans for operating the same, and valve means for controlling the supplyof motive fluid to the motor and to the piston means, respectively, torelease the brake disc from said seat on turning on the motivefluid tothe motor and for pressing the disc against said seat to stop therotation of the hammer and the motor on turning off the motive iluidthereto.

n 24. A revolvably acting impact clutch comprising a rotatable hammer, arotatable anvil having spaced jaws, impact members movably carried bythe hammer and movable by centrifugal force into the orbital path of thejaws to releasably connect the hammer to the anvil and to deliver asuccession of rotational impacts to said jaws in the rotation of thehammer relatively to the anvil, revolvable retracting means for theimpact members receiving rotation from the rotary motion imparted to theclutch and rotatable independently of the hammer about the axis thereofupon the termination of an impact to automatically move the impactmembers out of the orbital path of the jaws, and means for impartingrotary motion to the clutch.

25. A revolvably acting impact clutch comprising a, rotatable hammer, arotatable anvil having spaced jaws, impact members movably carried bythe hammer and movable by centrifugal force into the orbital path of thejaws to releasably connect the hammer to the anvil and to deliver asuccession of rotational impacts to said jaws in the rotation of thehammer relatively to the anvil, a revolvable retracting element for theimpact members rotatable relatively to the hammer about the axis thereofand receiving rotation fromrthe rotary motion imparted to the clutch,said element having cam means acting on the impact members in therotation of the element independently of and in the direction ofrotation of the hammer upon the termination of an impact toautomatically move the impact members out of the orbital path of thejaws, and means for imparting rotary motion to the clutch.

26. In a portable power driven impact tool of the character describedcomprising in combination, a power operated rotary motor, an impactclutch vhaving a rotatable hammer connected to the motor for rotationthereby, an anvil rotatably mounted with respect to the hammer andhaving spaced jaws, impact members movably carried by the hammer andmovable by centrifugal force into the orbital path of said jaws toreleasably connect the hammer to the anvil and to deliver a series ofrotational hammer blows to said jaws in the rotation of the hammerrelatively to the anvil, and means for automatically retracting theimpact members from the jaws upon the termination of an impact thereon,a brake mechanism for the motor, power means for applying and releasingsaid brake, means for conveying a motive uid to the motor and to thebrake operating means, respectively, manually operable means for turningon and oi the power supply to the motor, and

means responsive to the power fluid supplied to the tool to control theoperation of the brake operating means, said power iiuid responsivemeans acting to automatically release the brake on turning on of thepower supply to the motor and applying the brake to stop the rotation ofthe motor on turning off of the power supply thereto.

FRITHIOF P. FORSS.

